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Odour mortis, or the ‘smell of death’, refers to the chemicals released from the body during decomposition. Renowned forensic anthropologist Arpad Vass, who has studied the chemical changes occurring in the body after death for many years, recently shared the details of a particularly interesting scenario. The article, published in the May 2019 issue of Forensic Science International, details a fascinating case in which the occurrence of human decomposition was demonstrated based solely on chemical compounds in the air for the first time, without any human remains actually being found at the scene. The article doesn’t specify suspect or victim details, but anyone familiar with the case will recognise it instantly.

First, a brief introduction. In 2008, a woman was charged with the murder of her daughter, allegedly storing the victim’s body in the boot of her car for several days before disposing of the remains and dumping the car. Police had initially been alerted to the incident by the suspect’s parents, who had picked up their daughter’s abandoned car and noticed a foul decomposition-like odour coming from the vehicle. Coupled with the fact they had not seen their granddaughter in several weeks, the suspect’s mother promptly called 911.

The police soon took possession of the car and agreed that the scent of decomposition was emanating from the vehicle. Numerous cadaver dogs, specifically trained to detect odours from decaying bodies, alerted to the back of the car, further suggesting some kind of decomposing remains had been stored in the boot of the car. Fly pupae were also discovered. Entomological evidence is frequently associated with decomposing human remains, with flies and various other insects known to visit corpses to feed or lay eggs. Although no human remains were found in the car, several weeks later the body of the missing girl was found in a wooded area near the suspect’s home, and the case promptly turned into a murder investigation, with the victim’s mother as the prime suspect. However with minimal physical evidence linking the body to the suspect’s car, law enforcement turned to a somewhat unconventional tool to aid their investigation.

Various pieces of evidence were recovered from the vehicle, including segments of carpet, scrapings from the tyre wells, and various pieces of rubbish found in the car. Interestingly, investigators also collected some air samples from the boot of the car. Air can be sampled from remote locations using a technique that utilises air pumps to draw in gaseous analytes from the environment and capture them in a sorbent trap. This collection of trapped compounds can then be transported to a laboratory for analysis. In this case, about 35L of air was collected from the vehicle into a type of sorbent tube, then analysed using gas chromatography/mass spectrometry (GC/MS). GC/MS is a well-established analytical technique, allowing scientists to separate the individual chemicals in a mixture and identify those components. You can read more about how mass spectrometry works here.

This process allowed researchers to figure out exactly which volatile chemicals were present in the suspect’s vehicle and establish whether these are everyday compounds likely to be found in a car, or if they had some other source.

In the years leading up to this case a great deal of research had been conducted at the University of Tennessee’s Anthropological Research Facility. At this facility researchers were investigating, among other things, the odours produced during the decomposition of a human body. The odours created during this process are the result of volatile compounds produced as the body decomposes, and research has demonstrated that hundreds of individual chemical components are formed during this complex process. As part of research at the university, researchers had constructed a vast database of hundreds of chemicals detected during the process of human decomposition, including the different decomposition stages at which those chemicals appear. By comparing the chemicals detected in the vehicle with those stored in the database, it was possible to identify compounds known to be produced during the decomposition process. There was an 80% match between the compounds detected in the boot of the car and those chemicals considered to be relevant to human decomposition. Furthermore, unusually high levels of chloroform were also detected in the boot of the car.

The results from the air samples collected and chemical extracts from various other artefacts in the car led the researcher to conclude that there was a very high likelihood of a decomposition event occurring in the boot of the car. Many of the compounds detected in the vehicle could only be logically explained by the presence of decomposing remains.

Despite these findings (and various other pieces of evidence presented in court), the jury reached a verdict of not guilty for the charge of murder. Not too surprising an outcome, considering the use of air analysis to detect decomposition had not previously been used in a legal investigation. However in closing arguments, the defence stated that the victim had in fact been placed in the vehicle for transport (claiming the victim’s death had been accidental), ultimately confirming the results of the analysis.

Vass, A. A. Death is in the air: confirmation of decomposition without a corpse. Forensic Sci. Int. (2019). doi:10.1016/j.forsciint.2019.05.005

When human remains are discovered, investigators will often turn to routine methods such as fingerprinting, DNA profiling and the use of dental records to identify the individual. But in the absence of database records for comparison, such traditional techniques may not prove all that useful, and forensic scientists must look for new ways to identify the unknown.

In recent years the use of stable isotope analysis has aided forensic investigations, particularly in establishing the geographic origin of unidentified human remains. Isotopes are different forms of an element. For example, oxygen has three naturally occurring stable isotopes: O16, O17 and O18. These isotopes are incorporated into substances in the environment (such as water) in varying ratios. The relative abundance of isotopes can be influenced by various factors in a process known as isotopic fractionation. It has been found that isotopic ratios can be related to different regions of the world. For example, the tap water in one country may have a completely different isotopic signature in comparison to water in another country. How does this relate to the isotopes found in our bodies? Well, you are what you eat. As you consume food and water from a particular area, the atoms in our bodies express abundances similar to the food and water consumed.

This provides the basis for using isotope analysis to trace materials back to a certain geographic region. It has already been demonstrated that the isotopic analysis of bones, teeth and other bodily tissues can allow for individuals to be traced to particular locations, typically through the analysis of oxygen, hydrogen and sulphur isotopes. However last year, researchers at the University of Utah took a different approach, this time focusing on fingernails.

As with bones and teeth, the isotopic content of our fingernails will be affected by factors such as the food and water we consume. As fingernails are estimated to grow at a rate of 3-4mm per month, they are a prime target for studying isotopic patterns in an individual over a shorter timespan (less than six months as oppose to years). This is by no means the first study of isotope abundances in fingernails, but previous research has typically focussed on single timepoints rather than tracking the same individuals over time. As global travel becomes more commonplace, it is increasingly likely that human remains could have originated from any part of the world. Therefore, we need to understand how travel can cause changes in isotope abundances within the body.

This study aimed to establish whether fingernail isotope ratios were different in a group of local people in comparison to non-locals who had recently moved to the area (in this case Salt Lake City in the United States). Over a period of a year, fingernail clippings were collected at multiple timepoints from a group of volunteers, about half of which were local residents and the rest individuals who had recently arrived from various locations across the US and the world. The fingernail clippings were cleaned (to remove surface components and contaminants that could interfere with the analysis) and subjected to analysis by isotope ratio mass spectrometry (IRMS). IRMS is a particular type of mass spectrometry that allows us to measure the isotopic abundance of certain elements typically hydrogen, carbon, nitrogen, and oxygen. You can read more about IRMS here.

The isotope values of samples from residents were used to construct a baseline of expected values for the area, with isotope values from non-residents’ samples being compared with these. Initially, samples from non-residents showed a wide range of isotopic values, which is to be expected given they had only recently moved to the area. Some residents did fall within the expected range of locals, but these participants had moved from relatively nearby locations, which could explain the similar relative isotopic abundances. However after about 3 months, the fingernail isotopic patterns shifted until the non-residents could no longer be distinguished from the residents. This indicates that although the relative abundance of isotopes in our fingernails can shed some light on geographical movement, it can only provide information relating to the past few months. Inevitably there will always be a certain amount of error associated with such analyses, with variation from the likes of short-term travel and random dietary changes being impossible to account for.

The use of fingerprints as a means of identification has been successfully implemented worldwide. But how did the idea of using these unique impressions in a forensic setting first come about? Many scientists are known to have been involved in the early research relating to fingerprinting, dating right back to the 1600s, but Sir Francis Galton and William Herschel are widely recognised as the real pioneers of forensic fingerprinting.

However the story actually begins with the work of another man: Henry Faulds. In the late 1880s, the Scottish physician was working in Japan in a number of roles, one of which caused him to be involved in various archaeological digs. During this time he first stumbled upon the uniqueness of fingerprints after discovering prints left behind by craftsmen in old pieces of ceramic pottery. This allegedly inspired his notion of using fingerprints to identify criminals, at which point he promptly published an article in Nature detailing his thoughts on the matter. In his manuscript, “On the Skin-Furrows of the Hand”, Faulds suggested the possibility of using fingerprints to identify individuals, however did not provide anything to support his theory other than the anecdotal evidence of his own use of fingerprints to identify the perpetrator of a break-in at his hospital. Back in the UK, Faulds shared his ideas with Scotland Yard, but they unsurprisingly had no interest in this somewhat unsupported theory. Incidentally, Faulds also shared his work with Charles Darwin. Although Darwin did not pursue the research himself, he did forward the information to his cousin, Francis Galton. At the time, nothing came of this interaction.

Shortly after Fauld’s publication in Nature, William Herschel, a British civil servant who was based in India at the time, soon published a responding letter in Nature claiming he had been using fingerprints as a means of identification for years. A very public argument over who should claim credit for this idea ensued between the two scientists which lasted for years, though the world paid little attention. There was quite simply no data to support the claims of the two men.

A couple of years later, Sir Francis Galton once again enters the picture. Now heavily involved in the field of anthropometry (the study of measurements of the human body), he began working with Herschel to gather the much-needed data necessary to support the theory of fingerprints as a means of identification. Galton’s research allowed him to collect thousands of fingerprints and ultimately conclude that fingerprints were in fact unique to the individual, could persist on a surface for years if not decades, and could be easily used to develop a system of storing and comparing prints. Galton presented his findings at the Royal Institution, sharing his and Herschel’s research in fingerprinting as a means of identification. Based on Galton’s work, the use of fingerprinting was finally considered by Parliament in 1894, and was soon implemented in criminal investigations. Galton and Herschel were now viewed as the original pioneers of forensic fingerprinting, whereas Faulds later spent years fighting to be recognised as the true founder, petitioning to academic journals, newspapers and even the Prime Minister.

In 1892, anthropologist Juan Vucetich made history by using fingerprint evidence to positively identify the culprit in a criminal case. When the children of Francisca Rojas were found murdered, Vucetich implicated Rojas when a bloody print allegedly proved she was the murderer. Since then, the study and use of fingerprints has been a fundamental aspect of forensic investigations worldwide.

By training I’m a Forensic Archaeologist but currently work as a lecturer at Wrexham Glyndwr University teaching on the BSc (Hons) in Forensic Science. My day to day job is teaching student groups across all three years of the programme in a range of subjects such as Crime Scene Investigation, Anatomy & Pathology and the Forensic Investigation of Mass Fatalities. As well as delivering the theory I set up a lot of the practical work that the students do such as fingerprinting workshops, organ dissections and simulated crime scenes that we mock up in our Crime Scene House. I also supervise a number of student research projects mainly in the area of Taphonomy which we conduct on our ‘Body Farm’

What initially attracted you to this field of work?

I had always been interested in science and particularly forensic science and initially took a degree in Forensic Biology at Staffordshire. I always imagined that I would go on to work in a laboratory or doing fingerprint comparisons until I took a module in ‘Identification of Human Remains’. This really sparked my interest in human osteology and made me pursue a MSc in Forensic Archaeology and Crime Scene Investigation at Bradford University where I found my very niche area in search and recovery of human remains. I started teaching anatomy alongside completing my MSc and found a real love for being in the classroom. It gives me an ideal role in being able to share what I’ve learnt so far whilst still being able to pursue my own research and industry related work. Looking back now I can’t imagine not being a teacher. There’s something about introducing students to concepts they had never considered before that really exciting. And sometimes they come back to you later on in their academic careers and actually end up teaching you something; that’s a really rewarding feeling.

Can you tell us about the research you are currently involved in at Wrexham Glyndwr University?

We are really lucky here at Glyndwr to have Wales’ first and only Taphonomic Research Facility which is licensed by DEFRA. This ‘Body Farm’ allows us to conduct a number of research projects looking at decomposition which could necessarily be hosted by other universities without a dedicated, rural area in which to conduct their research. This coupled with a high calibre research lab in our Chemistry Department has really allowed both myself and students to expand research ideas. Current student projects which are out on the body farm include:

The effect of clandestine burial decomposition on soil chemistry and vegetation

How tattoo identification is effect by post mortem changes

A comparison of decomposition rates in fresh and stagnant water

I am also hoping to set up my own research once the temperature improves slightly and this will be looking at how oxygen deprivation (i.e. vacuum packing) affects taphonomic changes. This is a research project based on a pilot study I supervised, conducted last year by Shareei Singer at the University Centre Southend, and we hope to expand this further by looking at more samples, over a longer time frame whilst also improving the analysis methods used.

What are some of the biggest challenges in your field of work?

Teaching is a challenging role in the first place, but even more so at University level where there is an increased need to challenge students academically, and this can be particularly difficult field to get in to early in a professional career. I’m only 25 so it’s been very much a case of putting myself out there for any and every opportunity to prove myself and gain any experience I can. You really have to show not just your ability as an academic but also a drive and passion for the subject and the students. It is a highly competitive area, not only in terms of securing jobs in the first place, but then going on to conduct and publish research whilst still maintaining high quality, engaging session, for students every week. For me in particular, I find the sheer volume of books and journals I have to read, to ensure that my delivery keeps up with the speed that the area is progressing, a little daunting. But when it’s a subject that I’m passionate about, and books I would likely read anyway, it does make it easier!

Aside from research, are you often involved in police casework or consultancy work, and what does this typically involve?

I’m not currently involved in any active police work but I did only move up to North Wales around 6 months ago. It is something that I am very keen to start and hope to build up connections in the area to so this. I do some other consultancy work in different areas of forensic search. I work quite closely with UK-K9 who are a search dog training team. They specialise in training dogs to search for a variety of forensic evidence including human remains, explosives and drugs. We are currently working to improve the use of the human remains detection dogs on water and particularly in salt water setting such as costal searches. They are also involved in a lot of cold case reviews and large scale searches which I can offer an archaeological perspective on. I have also recently taken up a consultancy position with Kenyon International Emergency Services who deal with crisis incidents world-wide. I am currently awaiting deployment but once I am called in the role could be anything from collecting evidence at aeroplane crash sites to helping with disaster victim identification during natural disaster.

Do you have any words of advice for students wishing to pursue a career in your field of work?

For students wanting to go in to the forensic science generally just make sure you have it clear in your head before you start that it isn’t going to be how you see things portrayed in the media, I wouldn’t want you to be disappointed or put off once you start the course. I would say trying to get any sort of work experience is going to be crucial. Experience is essential nowadays but still almost impossible to get in crime related areas so think outside of the box a little bit. There are lots of labs you could do placements in that, although aren’t forensic can help you to learn and demonstrate key skills. I worked in a drinking water testing lab and in a haematology lab for a little while, both of which helped learn more about preventing cross contamination. But there are lots of other areas you can volunteer in such as becoming a PCSO, the Appropriate Adult services or any other charity that deals with victims of crime or offenders.

For students wanting to become educators I would say persevere. Remember what made you so passionate about that subject in the first place and share this with you students. It’s amazing how much more progress you make once you’ve learnt to foster this positive learning and collaborative environment. The planning and the marking will get easier, I promise!

My research focus, namely for my dissertation is a comparative study of the forensic science progression in Hong Kong over a 40 years time frame. Hong Kong is where I have been brought up, and forensic science in the city is always covered with the mysterious veil. In 1965, we had our first forensic case. Till today, more than 40 years have passed by, it will be essential to evaluate how much we had progress.

Other than the dissertation research, since my focus is on forensic anthropology and forensic archaeology, I am also doing different excavation field schools, projects, and osteology related research with other institutions.

Why is this research important to the field of forensic science and what do you hope to achieve by carrying out this research?

Technology and forensic techniques develop in a pace that we would never catch up with. However, due to constraints, not much comparative studies have been done, as an evaluation of the progress and development of the field, on the one hand. Sadly, funding is usually not entirely willing to sponsor studies of this sort, as they are hoping for new discovery most of the time, which likely lead to over generalization of ideas. Given the fact that forensics subjects heavily to experiences and contexts. Therefore, comparative study of forensic science is something that the profession needs yet tends to be overseen usually. On the other hand, a historical comparative study like the captioned one above, shows the same model over different time frames. It allows us to see the approach or policy from a macro level, namely environmental and political factors. In hope of this research, the government and the law enforcement will make improvements of their policies and models in order to facilitate the growth and application of forensic science in Hong Kong.

What does life as a postgraduate researcher entail?

Grad school life, as we all know, is tough. It is the kind of life that you have a full plate and always do not know where to start with. A lot of time management is involved, especially when I am also working alongside the study. People say you can use the senior year of undergraduate as a postgraduate tryout, I find this mostly correct! Also, other than studying, you are constantly looking for research and publication opportunities. Every time, when we are struggling, my pals and I keep asking ourselves, “why would we do this to ourselves.” But the sense of achievement is never better when you have accomplished something and survived a semester after another.

What are your plans for after you have completed your research?

After completing the existing project in the University of Leicester, I would be looking for PhD opportunities in either bioarchaeology, or biological anthropology.

Also, I have several real life forensic projects with police and other authorities ongoing and lined up. I am all excited and looking forward to all these amazing opportunities ahead!

Do you have any advice for students hoping to pursue a position in forensic research?

Keep your mind open!

First of all, forensic science itself is a relatively broad profession. Some of my friends switched from one discipline to another after trying out things, from forensic anthropology to law, from forensic pathology to forensic photography. You never know until you have tried. So first thing will be, to grasp as many opportunities as you can, then decide.

Once you made your choice, you also have to remember that forensic scientist is a relatively narrow yet competitive profession. What I mean is that, there is only certain demand in the authorities or law enforcement for forensic experts. If no one retires, you probably will not get a job. So it is always beneficial to have a broader, or second profession focus besides forensics.

Also, it is also very important to know that not every forensic scientist is good with doing research. Some are good with applying what we have learned, rather than doing research and making new discoveries. Be open minded, and do not get frustrated! Keep in mind that, either way we are making remarkable contribution.

I am a lecturer in Biological/Forensic Anthropology in the Skeletal Biology Research Centre, University of Kent. During term-time I teach all aspects of Human Evolution from early fossil hominins, hunter-gatherer societies, to methodologies used to reconstruct the last common ancestor (LCA). I also convene a forensic anthropology module where I teach forensic taphonomy, excavation and recovery, disaster victim identification and biometric identification. We are in the process of developing our MSc Forensic Osteology and Field Recovery Methods which will run from Sept. 2017 which is very exciting!

What initially attracted you to this field of work?

I wanted to become a forensic anthropologist from the first time I read Kathy Reich’s debut novel, Deja Dead. Of course, fiction is fiction however by the time I started researching the topic and where I could study forensics, I loved the topic for itself, for the science and so continued. I have turned more towards analytical chemistry techniques and human evolution in recent years; however, my interest in forensics continues, and my education and employment background remains relevant, as most forensic science disciplines, including forensic anthropology, have solid foundations in science, with the ‘forensic’ aspect being related to chain-of-custody maintenance and courtroom presentation.

Can you tell us about the research you are currently involved in at the University of Kent?

I conduct research into dietary ecology and subsistence patterns of past populations using stable isotope analysis. I have previously conducted such research on a population of wild Western chimpanzees, as correlates for the LCA; however, my current research focuses on medieval dietary reconstruction from East and West Europe. I am also currently involved in a project looking at the effects of bone turnover rates on stable isotope values and am currently investigating potential stable isotope methodologies that may have future use in forensic identification.

Has your work led you to be involved in any legal investigations? If so, what did this involve?

I worked as a forensic anthropology intern at the Netherlands Forensic Institute where I looked at decomposition of muscle tissue following submersion in water for my MSc thesis. Following this I worked as a forensic anthropology intern for the UN Mission in Kosovo in 2007 where I assisted in the identification and repatriation of victims of the Yugoslavian conflict. Subsequently I worked as an Associate Forensic Expert for the UN International Independent Investigation Commission in Lebanon which involved evidence collection and cataloging in the investigation of the assassination of former Lebanese Prime Minister Rafik Hariri and others.

Do you have any words of advice for students wishing to pursue a career in forensic anthropology?

Do your research but don’t be disheartened if you end up doing a different degree initially; as long as it’s not totally removed (e.g. doing a business degree when you then want to work in science) it is possible to get where you want to go without a straight path. I would advise doing as many unpaid internships as possible, this is where you gain valuable experience and make contacts for the future. Importantly realise that what you want can change as the years go by and this is fine….you may start out wanting to work constantly in the field, but then realise this is not viable for you and end up in a lab or a classroom, just go with whatever feels right for you.

I did a mixture of sciences and humanities at A Level and could never decide which I liked best, so I chose Archaeology and Anthropology as my first degree. There, I was fascinated by what you could tell about individuals by their skeletal remains, for example about hominid evolution. Then I discovered the burgeoning science of Forensic Anthropology, on a short course at Bradford University, and that was it, I was hooked! I love how you can glean all sorts of information from the smallest pieces of evidence. I have always loved logic problems, and forensic anthropology offers the most exciting puzzles. The fact that it is often confronting, challenging and disturbing, and could help to bring criminals to justice, just serves to add to its appeal for me.

Can you tell us about the research you are currently involved in at the University of Huddersfield?

I specialise in decomposition and taphonomy (the study of how bodies decay in different environments). To do this, I use an outdoor decomposition laboratory. I lead a research group currently doing research into the gases given off by decomposing cadavers (we use pigs that have died of natural causes), and comparing that to the efficiency of police dogs that are specially trained to find dead bodies. We’re also looking at how skin colour changes in surface or water environments, and trying to find ways to improve our estimation of post-mortem interval and post-mortem submersion interval. Other research is focussed on the taphonomic changes that occur to bone and teeth in hot, arid environments. I am also running a citizen science project in order to improve age estimation of unknown individuals from dental eruption. There is a webpage and online questionnaire for anyone who would like to help us build a large, modern set of tooth eruption data to see if dental eruption ages are changing.

Aside from research, are you often involved in police casework, and what does this typically involve?

Sometimes I am asked by the police to attend crime scenes or mortuaries to undertake forensic examination of decomposed or skeletonised remains. They can be either the victims of crime, or the remains of people who have gone missing. I will determine whether they are human or animal, and if they are human, I will estimate the age at death, sex, stature and ancestry of the individual(s), and try to say something about their lifestyle, disease, injury and how they died. I work in conjunction with forensic archaeologists and odontologists, as well as pathologists, to reach an identification. I also do consultancy for forensic science providers and, on occasion, a mass disaster company that helps to ‘clean up’ after disaster and repatriate the victims. I am involved in disaster victim identification and the Emergency Operations Centre.

The existence of so-called ‘body farms’ has sparked great interest in the media. Are there plans to establish such a facility in the UK? What are the primary challenges associated with this?

I believe that Human Taphonomy Facilities, or ‘Body Farms’ as they have become colloquially known, are vital for the advancement of forensic science. We owe all that we know already about human decomposition to the Forensic Anthropology Center at the University of Tennessee, and there is so much more to learn. We need to know how human conditions like diabetes, cancer, smoking and drug use affect our decomposition, which is something we cannot learn from experimenting with dead pigs. Unfortunately, a lot of the data generated by the ‘Body Farms’ in the USA and Australia are not directly relevant to forensic cases in the UK or Europe, because of the different climate, insects and scavengers. The UK is falling behind the USA and Australia by not having one of these outdoor laboratories where vital decomposition research can be done on donated cadavers. There was an attempt to establish a Body Farm in the UK in 2011, but this failed for a variety of financial and political reasons. I think the main obstacles to getting one set up in the UK are lack of funding, public awareness and rivalry between academic institutions. I hope that, in the near future, we will be able to create a facility where researchers, academics and practitioners will be able to work together to improve methods of search and recovery, post-mortem interval estimation and identification of human remains.

Do you have any words of advice for students wishing to pursue a career in forensic anthropology?

Forensic anthropology is a very competitive field, and there aren’t many jobs out there, so you need to be dedicated and determined. It can also be hard work and distressing, so decide carefully whether you want to pursue a career in it. The best way to make yourself stand out from the crowd of other applicants to jobs is to have experience, so try to get as much hands-on experience as you can. This doesn’t have to be forensic (although, of course, that would be preferable), but can be in archaeological units or museums or hospitals (or even zoos), somewhere where you can deal with human (or animal) bodies.

Images from Research

These pictures show the progression of decomposition in a small (10kg) pig. The first picture shows the pig in the fresh stage, when post-mortem interval was less than 24 hours. The second picture shows the pig in the active decay stage, 25 days later. The brown froth is decomposition fluid that has been agitated by the movement of maggots. The body was bloated with decomposition gases, but has now collapsed, and the intestines are escaping. The skin has desiccated, but the hair is still intact. The skin has darkened and become leathery in texture. The bones are becoming detached from the body.